Conductance-stable and integrated helical fiber electrodes toward stretchy energy storage and self-powered sensing utilization

Highly conductive and stretchable fibers are of great significance for wearable applications. Practical applications usually require high robustness and repeatability for these electronics under various mechanical deformations, which is a contradiction for most of existing strain-sensitive fibers conductors. In this work, core-shell hydrogel fiber with adjustable three-dimensional (3D) helical structure was fabricated, in which Ti3C2Tx (MXene)/poly(3,4-ethylenedioxythiophene) (PEDOT) were modified onto the surface of helical sodium alginate/polyacrylic acid (SA/PAA) hydrogel fibers via the combination of in situ polymerization and electrostatic assembly. The hybrid fiber possess a insensitive conductance (<5% resistance change) under various deformation, including stretching (0-800 %), bending (0-180 degrees), pressuring and twisting, attributed to both the double tortuous conductive network and pre-strain release from helical structure. Moreover, conductance-stable helical fibers could be appropriately assembled into coaxial energy fibers and integrated into fabric, both acting as strain-insensitive energy storage device and self-powered wearable sensor.